Base station antennas having arrays with frequency selective shared radiating elements

ABSTRACT

Base station antennas include a first array of radiating elements that is coupled to a first RF port through a first feed network, a second array of radiating elements that is coupled to a second RF port through a second feed network, and first and second circuit elements. The first circuit element has a first port coupled to the first feed network, a second port coupled to a first port of the second circuit element and a third port coupled to a first radiating element of the first array of radiating elements. The second circuit element has a second port coupled to a first radiating element of the second array of radiating elements and a third port coupled to the second feed network.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of, and claims priority under35 U.S.C. § 120 to, U.S. patent application Ser. No. 16/829,152, filedMar. 25, 2020, which in turn claims priority under 35 U.S.C. § 119 toChinese Patent Application Serial No. 201910282492.0, filed Apr. 10,2019, the entire content of each of which is incorporated herein byreference.

FIELD

The present invention relates to radio communications and, moreparticularly, to base station antennas for cellular communications.

BACKGROUND

Cellular communications systems are well known in the art. In a typicalcellular communications system, a geographic area is divided into aseries of regions that are referred to as “cells,” and each cell isserved by a base station. The base station may include basebandequipment, radios and base station antennas that are configured toprovide two-way radio frequency (“RF”) communications with subscribersthat are positioned throughout the cell. In many cases, the cell may bedivided into a plurality of “sectors,” and separate base stationantennas provide coverage to each of the sectors. The antennas are oftenmounted on a tower, with the radiation beam (“antenna beam”) that isgenerated by each antenna directed outwardly to serve a respectivesector. Typically, a base station antenna includes one or morephase-controlled arrays of radiating elements, with the radiatingelements arranged in one or more vertical columns when the antenna ismounted for use. Herein, “vertical” refers to a direction that isperpendicular to the horizontal plane that is defined by the horizon.Reference will also be made to the azimuth plane, which is a horizontalplane that bisects the base station antenna, and to the elevation plane,which is a plane extending along the boresight pointing direction of theantenna that is perpendicular to the azimuth plane.

A common base station configuration is the “three sector” configurationin which a cell is divided into three 120° sectors in the azimuth plane.A base station antenna is provided for each sector. In a three sectorconfiguration, the antenna beams generated by each base station antennatypically have a Half Power Beamwidth (“HPBW”) in the azimuth plane ofabout 65° so that each antenna beam provides good coverage throughout a120° sector. Three of these base station antennas will provide full 360°coverage in the azimuth plane. Typically, each base station antenna willinclude a so-called “linear array” of radiating elements that includes aplurality of radiating elements that are arranged in avertically-extending column. Each radiating element may have an azimuthHPBW of approximately 65° so that the antenna beam generated by thelinear array will have a HPBW of about 65° in the azimuth plane, Byproviding a column of radiating elements extending along the elevationplane, the HPBW of the antenna beam in the elevation plane may benarrowed to be significantly less than 65°, with the amount of narrowingincreasing with the length of the column in the vertical direction.

As demand for cellular service has grown, cellular operators haveupgraded their networks to support new generations of service. Whenthese new services are introduced, the existing“legacy” servicestypically must be maintained to support legacy mobile devices. Thus, asnew services are introduced, either new cellular base stations must bedeployed or existing cellular base stations must be upgraded to supportthe new services. In order to reduce cost, many cellular base stationssupport two, three, four or more generations of cellular service.However, due to local zoning ordinances and/or weight and wind loadingconstraints, there is often a limit as to the number of base stationantennas that can be deployed at a given base station. To reduce thenumber of antennas, many operators deploy antennas that communicate inmultiple frequency bands to support multiple different cellularservices.

There is considerable interest in base station antennas that include twolinear arrays of radiating elements that are used to provide service insome or all of the 1427-2690 MHz frequency band, which is often referredto as the “mid-band” frequency range. The two linear arrays of radiatingelements are typically mounted in side-by-side fashion. FIG. 1 is aschematic front view of a conventional base station antenna 10 thatincludes first and second columns 12-1, 12-2 of radiating elements 16.Each radiating element 16 is depicted in FIG. 1 (and others of thefigures herein) as an “X” to show that the radiating elements aredual-polarized cross-dipole radiating elements. Each column 12-1, 12-2of radiating elements 16 forms a respective linear array 14-1, 14-2 ofradiating elements 16. Antennas having the configuration shown in FIG. 1may be used in a variety of applications including 4×MIMO (i.e.,multi-input-multi-output) applications or as multi-band antennas thatsupport cellular service in two different sub-bands within the 1427-2690MHz frequency band (e.g., the linear arrays 14-1, 14-2 may operate indifferent, non-overlapping ones of, for example, the 1427-1518 MHz,1710-1880 MHz, 1850-1995 MHz, 1695-2180 MHz, 2300-2400 MHz, 2496-2690MHz and 2300-2690 MHz frequency sub-bands). In some cases, the lineararrays 14-1, 14-2 may be the only arrays included in the base stationantenna 10, while in other cases one or more additional arrays ofradiating elements (not shown) that operate in other frequency bandssuch as some or all of the low-band frequency range (which extends from617-960 MHz) or the high-band frequency range (which may include the3-4-3.8 GHz and/or the 5.1-5.8 GHz frequency bands) may also be includedin antenna 10.

It should be noted that herein, when multiple like or similar elementsare provided, they may be labelled in the drawings using a two-partreference numeral (e.g., arrays 14-1, 14-2). Such elements may bereferred to herein individually by their full reference numeral (e.g.,array 14-2) and may be referred to collectively by the first part oftheir reference numeral (e.g., the arrays 14).

SUMMARY

Pursuant to embodiments of the present invention, base station antennasare provided that include first and second RF ports, a first array ofradiating elements that is coupled to the first RF port through a firstfeed network, a second array of radiating elements that is coupled tothe second RF port through a second feed network, and first and secondcircuit elements. The first circuit element has a first port coupled tothe first feed network, a second port coupled to a first port of thesecond circuit element, and a third port coupled to a first radiatingelement of the first array of radiating elements, and the second circuitelement has a second port coupled to a first radiating element of thesecond array of radiating elements and a third port coupled to thesecond feed network.

In some embodiments, the first radiating element of the first array ofradiating elements may also be part of the second array of radiatingelements.

In some embodiments, the second circuit element may be a diplexer. Inother embodiments, the second circuit element may be a power dividerwith a filter on a first output port thereof.

In any of the above embodiments, the first circuit element may be adiplexer.

In some embodiments, the first array of radiating elements may consistof a first column of radiating elements and the second array ofradiating elements may consist of a second column of radiating elementsand one or more radiating elements of the first array of radiatingelements including the first radiating element of the first array ofradiating elements. In such embodiments, the first column of radiatingelements may be horizontally offset from the second column of radiatingelements.

In some embodiments, the first array of radiating elements may beconfigured to operate in a first frequency range and the second array ofradiating elements may be configured to operate in a second frequencyrange that partially, but not completely, overlaps with the firstfrequency range.

In some embodiments, the second circuit element may be configured topass signals input at the second RF port that are in a portion of thesecond frequency range that overlaps with the first frequency range tothe first radiating element of the second array of radiating elementsand to pass signals input at the second RF port that are in a portion ofthe second frequency range that does not overlap with the firstfrequency range to the first circuit element.

In some embodiments, the first circuit element may be configured to passsignals input at the second RF port that are in the portion of thesecond frequency range that does not overlap with the first frequencyrange to the first radiating element of the first array of radiatingelements.

In some embodiments, the first array of radiating elements may beconfigured to operate in some or all of the 1695-2690 MHz frequency bandbut not in the 1427-1518 MHz frequency band, while the second array ofradiating elements may be configured to operate in some or all of the1427-2690 MHz frequency band including at least a portion of the1427-1518 MHz frequency band and at least a portion of the 1695-2690 MHzfrequency band.

In some embodiments, the base station antenna may further include athird circuit element and a fourth circuit element, where the thirdcircuit element has a first port coupled to the second feed network viathe second circuit element, a second port coupled to a first radiatingelement of the second array of radiating elements and a third portcoupled to the first feed network via a first port of the fourth circuitelement, and the fourth circuit element has a second port coupled to thefirst feed network and a third port coupled to the first radiatingelement of the second array of radiating elements through the firstcircuit element.

In some embodiments, the third circuit element may be a diplexer and thefourth circuit element may be a diplexer or a low pass filter.

Pursuant to further embodiments of the present invention, base stationantennas are provided that include first and second RF ports, a firstplurality of radiating elements that are coupled to the first RF portthrough a first feed network, where the first plurality of radiatingelements are arranged in a first column and form a first array ofradiating elements, and a second plurality of radiating elements thatare coupled to the second RF port through a second feed network, wherethe second plurality of radiating elements are arranged in a secondcolumn. In these base station antennas, a first of the radiatingelements in the first column is further coupled to the second RF portthrough the second feed network, and the radiating elements in thesecond column and the first of the radiating elements in the firstcolumn comprise a second array of radiating elements.

In some embodiments, the first array of radiating elements may beconfigured to operate in some or all of the 1695-2690 MHz frequency bandbut not in the 1427-1518 MHz frequency band, while the second array ofradiating elements may be configured to operate in some or all of the1427-2690 MHz frequency band including at least a portion of the1427-1518 MHz frequency band and at least a portion of the 1695-2690 MHzfrequency band.

In some embodiments, the base station antenna further includes a firstcircuit element that has a first port coupled to the first feed network,a second port coupled to the second feed network and a third portcoupled to the first of the radiating elements in the first column.

In some embodiments, the base station antenna further includes a secondcircuit element that has a first port coupled to the second port of thefirst circuit element, a second port coupled to a first of the radiatingelements in the second column and a third port coupled to the secondfeed network.

In some embodiments, the second circuit element may be a diplexer or alow pass filter.

In some embodiments, the first circuit element may be a diplexer.

In some embodiments, the first column may be horizontally offset fromthe second column.

In some embodiments, the first array of radiating elements may beconfigured to operate in a first frequency range and the second array ofradiating elements may be configured to operate in a second frequencyrange that only partially overlaps with the first frequency range.

In some embodiments, the first circuit element may be configured to passsignals input at the second RF port that are in a portion of the secondfrequency range that does not overlap with the first frequency range tothe first of the radiating elements in the first array of radiatingelements.

Pursuant to still further embodiments of the present invention, basestation antennas are provided that include first and second RF ports, afirst vertical column of radiating elements, and a second verticalcolumn of radiating elements that is horizontally offset from the firstvertical column of radiating elements. More than half of the radiatingelements in the first vertical column of radiating elements are part ofa first array of radiating elements that is coupled to the first RF portthrough a first feed network, and more than half of the radiatingelements in the second vertical column of radiating elements are part ofa second array of radiating elements that is coupled to the second RFport through a second feed network. The second array of radiatingelements includes a first number of the radiating elements in the firstcolumn for RF signals that are within a first frequency range and asecond number of the radiating elements in the first column for RFsignals that are within a second frequency range that is lower than thefirst frequency range, the second number being larger than the firstnumber.

In some embodiments, the first number may be zero.

In some embodiments, the second array of radiating elements may includea third number of the radiating elements in the first column for RFsignals that are within a third frequency range that is lower than thesecond frequency range, the third number being larger than the secondnumber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of a conventional base station antennathat includes two linear arrays of radiating elements.

FIGS. 2A-2C are schematic front views of several conventional basestation antennas that have arrays of dual-polarized cross-dipoleradiating elements that have increased horizontal apertures thatgenerate antenna beams having reduced azimuth HPBWs.

FIG. 3A is a schematic front view of a base station antenna according toembodiments of the present invention.

FIG. 3B is a schematic block diagram illustrating the feed networks forthe base station antenna of FIG. 3A.

FIG. 4A is a front view of a printed circuit board based diplexer thatmay be used to implement either or both the first circuit element and/orthe second circuit element of the base station antenna of FIG. 3A.

FIG. 4B is a graph showing the simulated response of the diplexer ofFIG. 4A.

FIG. 5A is a front view of a printed circuit board based power dividerhaving a low pass filter at one output thereof that may be used toimplement the second circuit element of the base station antenna of FIG.3A.

FIG. 5B is a graph showing the simulated response of the powerdivider/low pass filter circuit of FIG. 5A.

FIG. 6A is a graph of the simulated azimuth HPBW as a function offrequency for the second array of radiating elements of the base stationantenna of FIGS. 3A-3B implemented using the diplexer of FIG. 4A as thefirst circuit element and the splitter/low pass filter circuit of FIG.5A as the second circuit element as compared to the azimuth HPBW for acomparable single column linear array of radiating elements.

FIG. 6B is a graph of the simulated gain as a function of frequency forthe second array of radiating elements of the base station antenna ofFIGS. 3A-3B implemented using the diplexer of FIG. 4A as the firstcircuit element and the splitter/low pass filter circuit of FIG. 5A asthe second circuit element as compared to the simulated gain for acomparable single column linear array of radiating elements.

FIG. 7 is a graph of the simulated azimuth HPBW as a function offrequency for the second array of radiating elements of the base stationantenna of FIGS. 3A-3B implemented using the diplexer of FIG. 4A as boththe first circuit element and the second circuit element as compared tothe azimuth HPBW for a comparable single column linear array ofradiating elements.

FIG. 8A is a schematic front view of a base station antenna according tofurther embodiments of the present invention.

FIG. 8B is a schematic block diagram illustrating the feed networks forthe base station antenna of FIG. 8A.

FIG. 9A is a schematic front view of a base station antenna according tostill further embodiments of the present invention that includes threecolumns of radiating elements.

FIG. 9B is a schematic block diagram illustrating the feed networks forthe base station antenna of FIG. 9A.

FIG. 10 is a schematic block diagram illustrating a base station antennaaccording to still further embodiments of the present invention.

DETAILED DESCRIPTION

One challenge in designing base station antennas is that the azimuthbeam width of a radiating element tends to vary as a function offrequency, with the azimuth beamwidth being wider when the radiatingelement operates at lower frequencies and narrower when the radiatingelement operates at higher frequencies. For operating frequency rangessuch as the traditional low-band frequency range (690-960 MHz), this wasnot a significant problem as the operating frequency range was not allthat broad. More difficulties were encountered in designing base stationantennas with linear arrays that could operate over the full extent ofthe traditional mid-band operating frequency range (1695-2690 MHz),although eventually suitable designs were developed. Recently, however,the 1427-1518 MHz frequency band has been opened for cellular service,and hence there is now demand for base station antennas having arrays ofradiating elements that can operate across the full 1427-2690 MHzfrequency band. Unfortunately, it is a significant challenge to designarrays of radiating elements that will operate over the full frequencyrange and that will have suitable azimuth beamwidths at both the lowerand upper ends of the operating frequency range.

Pursuant to embodiments of the present invention, base station antennasare provided that have two or more arrays of radiating elements thatshare one or more radiating elements. The shared radiating element(s)may be used to reduce the azimuth beamwidth of one or both of thearrays, with the amount of reduction in the azimuth beamwidth beingfrequency dependent. In particular, the reduction in azimuth beamwidthmay be relatively large in a lower portion of the operating frequencyband and may be relatively small (or non-existent) in an upper portionof the operating frequency band. Consequently, the shared radiatingelement(s) may be used to offset the natural tendency of the azimuthbeamwidth to increase with decreasing frequency, thereby allowing theantenna beam to have less variation as a function of frequency. As aresult, the base station antennas according to embodiments of thepresent invention may include one or more linear arrays that may be usedto support cellular service over any portion of the full 1427-2690 MHzfrequency band while having suitable azimuth beamwidths across theentire frequency band. Moreover, while the disclosure below will focuson base station antennas having mid-band arrays that operate in the1427-2690 MHz frequency band (or portions thereof), it will beappreciated that these same techniques may be used, for example, inlow-band or high-band arrays to either extend the operating frequencyband of those arrays and/or to reduce the amount of variation in theazimuth beamwidth over the operating frequency range.

The base station antennas according to embodiments of the presentinvention may share a radiating element of a first linear array with anadjacent second linear array. The shared radiating element ishorizontally offset from the second linear array and hence may be usedto narrow the azimuth beamwidth of the second linear array. The sharedradiating element may be coupled to the feed network for the secondlinear array through a frequency dependent circuit element such as adiplexer so that the shared radiating element will only substantiallycontribute to the antenna beam formed by the second array for RF signalsin selected (typically lower) frequency sub-bands. By sharing one ormore of the radiating elements of the first array with the second array,but only for certain frequency sub-bands, the azimuth beamwidth of theantenna beams formed by the second array may vary less as a function offrequency, and hence the base station antenna may form antenna beamshaving suitable shapes across the entire 1427-2690 MHz (or other)frequency band.

In some embodiments of the present invention, base station antennas areprovided that include a first array of radiating elements that iscoupled to a first RF port through a first feed network, a second arrayof radiating elements that is coupled to a second RF port through asecond feed network, and first and second circuit elements. The firstcircuit element has a first port coupled to the first feed network, asecond port coupled to a first port of the second circuit element, and athird port coupled to a first radiating element of the first array ofradiating elements. The second circuit element has a second port coupledto a first radiating element of the second array of radiating elementsand a third port coupled to the second feed network. The first circuitelement may comprise, for example, a diplexer. The second circuitelement may comprise, for example, a diplexer or a low pass or band passfilter.

In other embodiments, base station antennas are provided that include afirst plurality of radiating elements that are coupled to a first RFport through a first feed network, where the first plurality ofradiating elements are arranged in a first column and form a first arrayof radiating elements, and a second plurality of radiating elements thatare coupled to a second RF port through a second feed network, where thesecond plurality of radiating elements are arranged in a second column.A first of the radiating elements in the first column is further coupledto the second RF port through the second feed network, and the radiatingelements in the second column and the first of the radiating elements inthe first column comprise a second array of radiating elements. Each ofthe above-described base station antennas may include a second array ofradiating elements that includes a first column of radiating elements aswell as one or more horizontally offset “shared” radiating elements thatare part of both the second array of radiating elements as well as beingpart of a first array of radiating elements.

Base station antennas have been previously suggested that includeantenna arrays that comprise a linear array of radiating elements plusone or more additional radiating elements that are horizontally offsetfrom the linear array. Such arrays have typically been employed tonarrow the width of the antenna, since the horizontally offset radiatingelements act to narrow the azimuth beamwidth of the array, therebyallowing smaller radiating elements to be used while still achieving,for example, a 65° azimuth HPBW. FIGS. 2A-2C are schematic views ofthree base station antennas that each include two arrays of radiatingelements where each array includes a linear array of radiating elementsplus a horizontally offset radiating element.

Referring first to FIG. 2A, a conventional base station antenna 30 isdepicted that includes first and second columns 32-1, of radiatingelements 36. The base station antenna 30 may be identical to the basestation antenna 10 of FIG. 1, except that (1) it includes fewerradiating elements 36 (and hence has a wider elevation HPBW) and (2) theradiating elements 36 are grouped differently to form the two arrays34-1, 34-2. To help highlight which radiating elements 36 form eacharray 34-1, 34-2, polygons have been drawn around each array 34. Thefirst array 34-1 includes the bottom five radiating elements 36 in theleft-hand column 32-1 as well as the bottom radiating element 36 in theright-hand column 32-2, while the second array 34-2 includes the topfive radiating elements 36 in the right-hand column 32-2 as well as thetop radiating element 36 in the left-hand column 32-1. Thus, the firstarray 34-1 has an L-shape and the second array 34-2 has an upside-downL-shape. Since each array 34-1, 34-2 includes a radiating element 36that is in the opposite column 32-2, 32-1, respectively, the horizontalaperture of each array 34-1, 34-2 is increased, with a commensuratereduction in the azimuth beamwidth. One disadvantage, however, of thisdesign is that it requires adding an extra radiating element 36 to eachcolumn 32-1, 32-2 (to allow one row of each array to include tworadiating elements 36), which increases the length and cost of theantenna 30 without providing any reduction in the elevation beamwidthand/or any appreciable increase in the gain of the antenna 30,

FIG. 2B is a schematic front view of a conventional base station antenna40 that increases the horizontal aperture without the need for adding anextra radiating element in each column. The base station antenna 40includes two columns 42-1, 42-2 of radiating elements 46 that form firstand second so-called “Y-shaped” arrays 44-1, 44-2 (note that each array44 is one radiating element short of having a true “Y-shape”). The basestation antenna 40 is similar to the base station antenna 10 of FIG. 1,except that it again includes fewer radiating elements 46 and the bottomradiating element 46 in each column 42-1, 42-2 is switched to be part ofthe array 44 formed by the rest of the radiating elements 46 in theopposite column 42-1, 42-2. Since each array 44-1, 44-2 includes aradiating element 46 that is in the opposite column 42-1, 42-2, thehorizontal aperture of each array 44-1, 44-2 is increased, with acommensurate reduction in the azimuth beamwidth. Moreover, the basestation antenna 40 does not include two radiating elements 46 in anyrow, and hence does not suffer from the cost and size disadvantagesassociated with base station antenna 30. A disadvantage, however, of thedesign of base station antenna 40 is that the physical distance betweenthe bottom two radiating elements 46 in each array 44-1, 44-2 isincreased (since the physical distance is taken along a diagonal asopposed to simply being the vertical distance between the two radiatingelements 46), and this results in off-axis grating lobes in theresultant radiation patterns formed by the first and second arrays 44-1,44-2. These grating lobes reduce the gain of the antenna 40, and mayalso result in interference with neighboring base stations.

FIG. 2C is a schematic front view of another conventional base stationantenna 50 that has arrays with increased horizontal apertures. The basestation antenna 50 is disclosed in U.S. Pat. No. 8,416,142 to Göttl. Asshown in FIG. 2C, the base station antenna 50 includes first and secondcolumns 52-1, 52-2 of dual-polarized cross-dipole radiating elements 56.The radiating elements 56 in the left-hand column 52-1 are part of afirst array 54-1, and the radiating elements 56 in the right-hand column52-2 are part of a second array 54-2. The antenna 50 further includesfirst and second centrally located radiating elements 58-1, 58-2, whichmay be identical in design to the radiating elements 56. One dipoleradiator of each centrally-located radiating element 58-1, 58-2 is partof the first array 54-1 and the other dipole radiator of eachcentrally-located radiating element 58-1, 58-2 is part of the secondarray 54-2. Thus, the first array 54-1 includes six dipole radiators foreach polarization (namely the five dipole radiators at each polarizationincluded in the radiating elements in the first column 52-1, the +45°dipole radiator of centrally-located radiating elements 58-1, and the−45° dipole radiator of centrally-located radiating element 58-2).Likewise, the second array 54-2 includes six dipole radiators for eachpolarization (namely the five dipole radiators at each polarizationincluded in the radiating elements in the second column 52-2, the −45°dipole radiator of centrally-located radiating element 58-1, and the+45° dipole radiator of centrally-located radiating element 58-2). Thecentrally-located radiating elements 58-1, 58-2 act to narrow theazimuth beamwidth by, increasing the horizontal aperture of each array54-1, 54-2, thereby allowing for reduction in the size of the individualradiating elements 56, 58.

Embodiments of the present invention will now be discussed in moredetail with reference to the remaining figures.

FIG. 3A is a schematic front view of a base station antenna 100according to embodiments of the present invention. FIG. 3B is aschematic block diagram illustrating the feed networks for the basestation antenna 100 of FIG. 3A.

As shown in FIG. 3A, the base station antenna 100 includes a pluralityof radiating elements 114, 116 that are mounted to extend forwardly froma reflector 110. The base station antenna 100 further includes firstthrough fourth RF ports 120-1 through 120-4. The radiating elements 114,116 are mounted to form first and second vertically-extending columns130-1, 130-2 of radiating elements 120. Radiating elements 114-1 through114-9 along with radiating elements 116-12 and 116-13 form a first array140-1 of radiating elements (array 140-1 is outlined in a dashed box inFIG. 3B). Radiating elements 116-1 through 116-13 form a second array140-2 of radiating elements (array 140-2 is outlined in a solid box inFIG. 3B). As shown in FIG. 3A, the first array 140-1 is a verticallyextending linear array of radiating elements while the second array140-2 is a generally “L-shaped” array of radiating elements. As shown inFIG. 3A, radiating elements 116-12 and 116-13 are shared radiatingelements that are part of both the first array 140-1 and the secondarray 140-2.

Each radiating element 114, 116 may comprise, for example, adual-polarized slant −45°/+45° cross-dipole radiating element.Embodiments of the present invention, however, are not limited to suchradiating elements, and it will be appreciated that other radiatingelements such as single-polarization dipole radiating elements,single-polarization and/or dual-polarization patch radiating elements,box dipole radiating elements, loop radiating elements and the like maybe used in place of the dual-polarized slant −45°/+45° cross-dipoleradiating elements 114, 116 that are schematically illustrated in FIG.3A using large X's (the radiating elements 114 are shown using dashedX's to more clearly distinguish the two different types of radiatingelements). It will also be appreciated that the same type of radiatingelements may be used to implement the radiating elements 114 and theradiating elements 116, or that a first type of radiating elements maybe used to implement the radiating elements 114 and a second, differenttype of radiating element may be used to implement the radiatingelements 116. In some embodiments, the radiating elements 116 may bedesigned to operate in a first frequency range (e.g., the 1427-2690 MHzfrequency band) while the radiating elements 114 may be designed tooperate in only a portion of the first frequency range that is at thehigher end of the frequency range (e.g., the 1695-2690 MHz frequencyband). In such embodiments, it may be possible to use smaller, lessexpensive radiating elements to implement the radiating elements 114 (ascompared to the radiating elements 116).

While a total of nine radiating elements 114 and a total of thirteenradiating elements 116 are shown in FIG. 3A, it will be appreciated thatany appropriate number of radiating elements 114, 116 may be included inbase station antenna 100. Moreover, the first and second columns 130-1,130-2 need not include the same number of radiating elements, althoughin many cases it may be advantageous for the two columns 130 to includethe same number of radiating elements. The number of radiating elements114, 116 included in each column 130 may be selected, for example, tomeet specified gain and/or elevation beamwidth requirements. Moreover,while the base station antenna 100 is illustrated as having a total oftwo arrays 140 of radiating elements, it will be appreciated thatadditional arrays of radiating elements (not shown) may be included onthe antenna 100. For example, one or more arrays of low-band radiatingelements, one or more arrays of high-band radiating elements, and/or oneor more additional arrays of mid-band radiating elements may be includedin some embodiments.

In FIG. 3A, the base station antenna 100 is shown as including twoshared radiating elements 116-12, 116-13 that are located at the bottomof the first column 130-1 of radiating elements. It will be appreciated,however, that embodiments of the present invention are not limitedthereto. In other embodiments, a single shared radiating element or morethan two shared radiating element may be included in the antenna 100.For example, only the bottom radiating element 116-12 in the firstcolumn 130-1 could be a shared radiating element. Likewise, instead ofsharing one or more radiating elements that are at the bottom of acolumn 130, one or more radiating elements 116 could be shared betweenthe first and second arrays 140-1, 140-2 that is/are at the top a column130 and/or in a middle portion of a column 130. When multiple sharedradiating elements are provided, they may or may not be adjacent eachother in a column 130.

FIG. 3B is a schematic block diagram of the base station antenna 100 ofFIG. 3A that illustrates two of the feed networks 150 thereof. As shownin FIG. 3B, feed network 150-1 is used to pass RF signals between thefirst RF port 120-1 and the radiating elements 114-1 through 114-9 and116-12 and 116-13 that are included in the first array 140-1, while feednetwork 150-2 is used to pass RF signals between the second RF port120-2 and the radiating elements 116-1 through 116-13 that are includedin the second array 140-2. In each case, the RF signals are passed tothe −45° radiators of the radiating elements 114, 116. In FIG. 3B, onlythe feed networks 150-1, 150-2 for the −45° RF ports 120-1, 120-2 areshown, and the feed networks 150 for the +45° RF ports 120-3, 120-4 areomitted to simplify the drawing. It will be appreciated that the feednetworks 150 for the +45° RF ports 120-3, 120-4 may be identical to feednetworks 150-1, 150-2, respectively, except that the feed networks 150for the +45° RF ports 120-3, 120-4 connect to the +45° dipole radiatorsof the radiating elements 114, 116 in the arrays 140-1, 140-2, whereasthe feed networks 150-1, 150-2 connect to the −45° dipole radiators ofthe radiating elements 114, 116.

In the description that follows, various ports of the phase shifters 152and other circuit elements may be referred to as being “input ports” or“output ports.” The “input” and “output” labels are made under theassumption that an RF signal that is to be transmitted by base stationantenna 100 (a “transmit RF signal”) is passing through one of the feednetworks 150. It will be appreciated that with respect to RF signalsreceived by base station antenna 100 each “output port” will operate asan input port and each “input port” will operate as an output port dueto the bidirectional nature of the RF signals passed through basestation antenna 100.

The first feed network 150-1 includes a first phase shifter assembly152-1 that has an input that is coupled to the first RF port 120-1 andfive outputs 154. Each phase shifter assembly 152 may include a powersplitter/combiner and a phase shifter (not shown separately). The powersplitter/combiner may be a component that divides an RF transmit signalinto a plurality of sub-components and that combines a plurality ofsub-components of a received RF signal into a single combined RF signal.The phase shifter may be a component that imparts a phase taper to thevarious components of the transmit and receive RF signals. The phaseshifter may be an adjustable phase shifter that can be remotelycontrolled to vary the amount of phase taper applied to the transmit andreceive RF signals in order to impart a desired amount of electricaldowntilt to the antenna beam. Suitable phase shifter assemblies aredisclosed, for example, in U.S. Patent Publication No. 2017/0365923, theentire content of which is incorporated herein by reference.

RF signals input at RF port 120-1 enter the phase shifter assembly 152-1at the input port thereof and are divided into five sub-components bythe power splitter/combiner that is integrated into the phase shifterassembly 152-1. The phase shifter assembly 152-1 may be adjusted toapply a phase taper to the five sub-components of the RF signal in orderto apply a desired amount of electronic downtilt to the elevation angleof the antenna beam formed by the first array 140-1. Each output 154 ofphase shifter assembly 152-1 is coupled to a sub-array 112 of theradiating elements 114, 116. In particular, the first output 154 iscoupled to a first sub-array 112-1 that includes radiating elements114-1 through 114-3, the second output 154 is coupled to a secondsub-array 112-2 that includes radiating elements 114-4 and 114-5, thethird output 154 is coupled to a third sub-array 112-3 that includesradiating elements 114-6 and 114-7, the fourth output 154 is coupled toa fourth sub-array 112-4 that includes radiating elements 114-8 and114-9, and the fifth output 154 is coupled to a fifth sub-array 112-5that includes radiating elements 116-12 and 116-13. As is further shownin FIG. 3B, the fifth output 154 of phase shifter assembly 150-1 iscoupled to the fifth sub-array 112-5 through a first circuit element160. The first circuit element 160 may be a frequency selective devicesuch as, for example, a diplexer or other multiplexer.

The second feed network 150-2 includes a second phase shifter assembly152-2 that has an input that is coupled to the second RF port 120-2 andfive outputs 154. RF signals input at RF port 120-2 enter the phaseshifter assembly 152-2 at the input port thereof and are divided intofive sub-components by a power splitter/combiner that is integrated intothe phase shifter assembly 152-2. The phase shifter assembly 152-2 maybe adjusted to apply a phase taper to the five sub-components of the RFsignal in order to electronically downtilt the elevation angle of theantenna beam formed by the second array 140-2. Each output 154 of phaseshifter assembly 152-2 is coupled to a respective sub-array 112 of theradiating elements 116. In particular, the first output 154 is coupledto a sixth sub-array 112-6 that includes radiating elements 116-1through 116-3, the second output 154 is coupled to a seventh sub-array112-7 that includes radiating elements 116-4 and 116-5, the third output154 is coupled to an eighth sub-array 112-8 that includes radiatingelements 116-6 and 116-7, the fourth output 154 is coupled to a ninthsub-array 112-9 that includes radiating elements 116-8 and 116-9, andthe tenth output 154 is coupled to a tenth sub-array 112-10 thatincludes radiating elements 116-10 and 116-11 and is also coupled to thefifth sub-array 112-5 that includes radiating elements 116-12 and116-13. As is shown in FIG. 3B, the fifth output 154 of phase shifterassembly 152-2 is coupled to the fifth and tenth sub-arrays 112-5,112-10 through a second circuit element 170. The second circuit element170 may also be a frequency selective device such as, for example, adiplexer or other multiplexer or a power divider that has a filter suchas a low-pass or band-pass filter on one of the output legs thereof.

The first circuit element 160 and the second circuit element 170 may beconfigured to allow the radiating elements 116-12 and 116-13 to beshared by the first and second arrays 140-1, 140-2 in afrequency-selective fashion. In one example embodiment, the firstcircuit element 160 may be a diplexer having first and second frequencyselective ports 162-1, 162-2 and a “common” port 162-3. As discussedabove, the first array 140-1 of base station antenna 100 is designed totransmit and receive RF signals in the 1695-2690 MHz frequency band,while the second array 140-2 is designed to transmit and receive RFsignals in the 1427-1518 MHz and 1695-2690 MHz frequency bands. Thefirst frequency selective port 162-1 of diplexer 160 is thus configuredto pass RF signals in the 1695-2690 MHz frequency band, but to block RFsignals in the 1427-1518 MHz frequency band. The second frequencyselective port 162-2 of diplexer 160 is configured to pass RF signals inthe 1427-1518 MHz frequency band, but to block RF signals in the1695-2690 MHz frequency band. The “common” port 162-3 is configured topass RF signals in both the 1427-1518 MHz and 1695-2690 MHz frequencybands.

In some embodiments, the second circuit element 170 may likewise beimplemented as a diplexer having first and second frequency selectiveports 172-1, 172-2 and a “common” port 172-3. The first frequencyselective port 172-1 of diplexer 170 is configured to pass RF signals inthe 1427-1518 MHz frequency band, but to block RF signals in the1695-2690 MHz frequency band. The second frequency selective port 172-2of diplexer 170 is configured to pass RF signals in the 1695-2690 MHzfrequency band, but to block RF signals in the 1427-1518 MHz frequencyband. The “common” port 172-3 of diplexer 170 is configured to pass RFsignals in both the 1427-1518 MHz and 1695-2690 MHz frequency bands.

The base station antenna 100 may operate as follows. A first RF signalthat is within the 1695-2690 MHz frequency band may be input at RF port120-1. The first RF signal is divided into five sub-components and phaseshifted by the phase shifter assembly 152-1. The first through fourthsub-components of the RF signal are passed to the respective sub-arrays112-1 through 112-4 where the sub-components are radiated by radiatingelements 114-1 through 114-9. The fifth sub-component is passed to port162-1 of diplexer 160. Since the sub-component is within the 1695-2690MHz “pass-band” of port 162-1, the fifth sub-component will pass to thecommon port 162-3 of diplexer 160 and from there to the fifth sub-array112-5 where the fifth sub-component of the RF signal is radiated byradiating elements 116-12 and 116-13. Since the fifth sub-component isnot within the 1427-1518 MHz “pass-band” of port 162-2, the fifthsub-component will not pass to the second circuit element 170 or to anyradiating elements in the second column 130-2 of radiating elements.Thus, the first RF signal that is input at RF port 120-1 is passed to afirst array 140-1 of radiating elements that includes radiating elements114-1 through 114-9 and radiating elements 116-12 and 116-13. The firstarray 140-1 is a linear array of radiating elements, and the diplexer160 has no impact on RF signals entered at the first RF port 120-1 otherthan incurring a small insertion loss.

A second RF signal may be input at RF port 120-2. As discussed above,the second RF signal may either be within the 1427-1518 MHz frequencyband or within the 1695-2690 MHz frequency band. The second RF signal isdivided into five sub-components and phase shifted by the phase shifterassembly 152-2. The first through fourth sub-components of the second RFsignal are passed to the respective sub-arrays 112-6 through 112-9 wherethe sub-components are radiated by radiating elements 116-1 through116-9. The fifth sub-component is passed to the common port 172-3 ofdiplexer 170. Operation of the diplexer 170 will vary depending upon thefrequency of the second RF signal.

In particular, if the second RF signal that is input at RF port 120-2 isin the 1695-2690 MHz frequency band, the fifth sub-component of thissignal will pass to frequency selective port 172-2 of diplexer 170,which has a 1695-2690 MHz pass band. Consequently, the fifthsub-component of the second RF signal will pass through the diplexer 170to the tenth sub-array 112-10 of radiating elements (radiating elements116-10 and 116-11). As the sub-component is not within the 1427-1518 MHzpass-band of frequency selective port 172-1, the fifth sub-componentwill not pass to the first diplexer 160. Thus, signals input at RF port120-2 that are within the 1695-2690 MHz frequency band will be radiatedonly by radiating elements 116-1 through 116-11 of the second array140-2, and hence the second array 140-2 will operate as a second lineararray of radiating elements.

If the second RF signal that is input at RF port 120-2 is in the1427-1518 MHz frequency band, the fifth sub-component of this signalwill again pass through the common port 172-3 of diplexer 170. As thefifth sub-component is not within the 1695-2690 MHz pass-band offrequency-selective port 172-2, the subcomponent will not pass to thetenth sub-array 112-10 of radiating elements (radiating elements 116-10and 116-11). As the fifth sub-component is within the 1427-1518 MHzpass-band of frequency-selective port 172-1, the fifth subcomponent willpass to frequency selective port 162-2 of the first diplexer 160, andwill then pass through the first diplexer 160 to the fifth sub-array ofradiating elements 112-5. Thus, signals input at RF port 120-2 that arewithin the 1427-1518 MHz frequency band will be radiated by radiatingelements 116-1 through 116-9 and 116-12 and 116-13 of the second array140-2 (and not by radiating elements 116-10 and 116-11). Thus, when boththe first and second circuit elements 160, 170 are implemented asdiplexers, the second array 140-2 will operate as either a linear arrayor as a so-called Y-shaped array depending upon the frequency of theinput signal.

Thus, in each case, a second RF signal input at RF port 120-2 will beradiated by eleven of the radiating elements 116. The difference,however, is that if the RF signal is in the higher 1695-2690 MHzfrequency range, the radiating elements used to generate the antennabeam are all in a single vertically disposed column 130-2, and hence thesecond array 140-2 does not act to shrink the azimuth beamwidth of thegenerated antenna beam. In contrast, if the RF signal is in the lower1427-1518 MHz frequency range, two of the radiating elements 116(radiating elements 116-12 and 116-13) that are used to generate theantenna beam are horizontally offset from the remaining nine radiatingelements (116-1 through 116-9), and this horizontal offset acts toshrink the azimuth beamwidth of the generated antenna beam. The amountthat the azimuth beamwidth shrinks may be a function of (1) thehorizontal distance between the two columns 130-1, 130-2 and (2) theratio of the power of the sub-components of the second RF signal that isdelivered to radiating elements 116-1 through 116-9 as compared to thepower of the fifth sub-component of the second RF signal that isdelivered to radiating elements 116-12 and 116-13.

As the above discussion makes clear, the base station antenna 100 may beconfigured to reduce the azimuth beamwidth of RF signals input at RFport 120-2 that are in the lower 1427-1518 MHz frequency band, withoutperforming any such reduction in the azimuth beamwidth of RF signalsinput at RF port 120-2 that are in the higher 1695-2690 MHz frequencyband. This approach is used to offset the inherent widening of theazimuth beamwidth that occurs with decreasing frequency in order toprovide an array of radiating elements 140-2 that exhibits lessvariation in azimuth beamwidth across the ultra-wide 1427-2690 MHzfrequency band.

In other embodiments, the second circuit element 170 may alternativelybe implemented as a power divider having a low-pass filter (or aband-pass filter) on one of the “output” ports thereof (namely port172-1). The low-pass (or band-pass) filter is configured to pass RFsignals in at least the 1427-1518 MHz frequency band while blocking RFsignals in the 1695-2690 MHz frequency band. In this embodiment, thesecond circuit element has two common ports (ports 172-2 and 172-3) thatpass signals in the full 1427-2690 MHz frequency range and one frequencyselective port (port 172-1). The frequency selective port 172-1 may bedesigned to only pass signals in the 1427-1518 MHz frequency band, ormay be designed to have a “soft” roll-off so that it allows less powerto pass with increasing frequency above about 1518 MHz.

When the second circuit element 170 is implemented as a power dividerwith a filter on one port, the base station antenna 100 may operate asfollows. A first RF signal that is within the 1695-2690 MHz frequencyband may be input at RF port 120-1. This first RF signal is passed to afirst array 140-1 of radiating elements that includes radiating elements114-1 through 114-9 in the exact same manner as described above withrespect to the embodiment where the second circuit element 170 isimplemented as a diplexer. Accordingly, further description thereof willbe omitted.

A second RF signal may be input at RF port 120-2 that is within eitherthe 1427-1518 MHz frequency band or the 1695-2690 MHz frequency band.The second RF signal is divided into five sub-components and phaseshifted by the phase shifter assembly 152-2. The first through fourthsub-components of the RF signal are passed to the respective sub-arrays112-6 through 112-9 where the sub-components are radiated by radiatingelements 116-1 through 116-9. The fifth sub-component is passed to thecommon port 172-3 of the power divider/low pass filter 170. Once again,operation of the second circuit element 170 will vary depending upon thefrequency of the second RF signal.

In particular, if the signal that is input at RF port 120-2 is in the1695-2690 MHz frequency band, the fifth sub-component of this signalwill pass from the common port 172-3 of power divider/filter 170 tocommon port 172-2 and be provided to the tenth sub-array 112-10 ofradiating elements (radiating elements 116-10 and 116-11). The low-band(or pass-band) filter on frequency selective port 172-1 blocks the RFsignal (since it is in the higher 1695-2690 MHz frequency band), andhence the second array 140-2 will operate as a linear array thatincludes radiating elements 116-1 through 116-11 in response to an RFsignal in the 1695-2690 MHz frequency band.

If the RF signal that is input at RF port 120-2 is in the 1427-1518 MHzfrequency band, the fifth sub-component of this signal will again passthrough the common port 172-3 of power divider/filter 170. As thesub-component is within the 1427-1518 MHz pass-band offrequency-selective port 172-1, the subcomponent will pass to the secondport 162-2 of diplexer 160, and will then pass through the diplexer 160to the fifth sub-array 112-5 (i.e., to radiating elements 116-12 and116-13). Moreover, as the second port 172-2 of power divider/filter 170is a common port, the signal will also pass to the tenth sub-array112-10 of radiating elements (radiating elements 116-10 and 116-11). Thepower divider included in power divider/filter 170 can be set to equallyor unequally split the power of the fifth sub-component of the RF signaldepending upon a desired amount of narrowing of the azimuth beamwidth.Thus, when the second circuit element 170 is implemented as a powerdivider/filter 170, the second array 140-2 will operate as an L-shapedarray that includes radiating elements 116-1 through 116-13 in responseto RF signals in the 1427-1518 MHz frequency range.

As the above discussion makes clear, the second array 140-2 will operatedifferently based on which implementation is selected for the secondcircuit element 170. In effect, the diplexer implementation of thesecond circuit element 170 results in a Y-shaped second array 140-2 forRF signals in the 1427-1518 MHz frequency band, while the powerdivider/filter implementation of the second circuit element 170 resultsin an L-shaped second array 140-2 for RF signals in the 1427-1518 MHzfrequency band. With both implementations, the second array 140-2operates as a linear array in response to signals in the 1695-2690 MHzfrequency band.

FIG. 4A is a front view of a printed circuit board based diplexer 200that may be used to implement either or both the first circuit element160 and/or the second circuit element 170 of the base station antenna100 of FIGS. 3A-3B in example embodiments of the present invention.

As shown in FIG. 4A, the diplexer 200 is implemented on a microstripprinted circuit board 210. The microstrip printed circuit board 210 mayinclude a dielectric substrate 212 that has a ground plane metallizationlayer (not shown) covering a back side of the substrate and a metal“trace” pattern 214 on the front side of the substrate 212. The tracesof the trace pattern 214 form microstrip transmission line segments andresonating stubs. The metal trace pattern 214 includes three “ports”which represent locations where RF signals may be input and/or outputfrom the diplexer 200. These ports include a first common port 220-1 anda pair of frequency selective ports 220-2, 220-3. A first trace definesa first microstrip transmission line segment 230-1 that connects port220-1 to port 220-2, and a second trace defines a second microstriptransmission line segment 230-2 that connects port 220-1 to port 220-3.The resonating stubs 216 are designed to form a filter along eachmicrostrip transmission line segment 230-1, 230-2 that passes RF signalsin certain frequency bands while rejecting RF signals in other frequencybands.

FIG. 4B is a graph showing the simulated response of the diplexer 200 ofFIG. 4A. Curve 240-1 in FIG. 4B shows the magnitude of the signal outputat port 220-2 in response to an RF signal input at port 220-1, as afunction of frequency, while curve 240-2 shows the magnitude of thesignal output at port 220-3 in response to an RF signal input at port220-1, as a function of frequency. As shown by curve 240-2 in FIG. 4B,signals in the 1427-1518 MHz frequency band that are input to thediplexer 200 at port 220-1 pass with almost no attenuation to port220-3, while signals in the 1695-2690 MHz frequency range aresubstantially or completely blocked at port 220-3. In contrast, as shownby curve 240-1 in FIG. 4B, signals in the 1695-2690 MHz frequency bandthat are input to the diplexer 200 at port 220-1 pass with almost noattenuation to port 220-2, while signals in the 1427-1518 MHz frequencyrange are substantially or completely blocked at port 220-2.

FIG. 5A is a front view of a printed circuit board based power divider250 having a low pass filter at one output thereof that may be used toimplement the second circuit element 170 of the base station antenna 100of FIGS. 3A-3B in an example embodiment of the present invention. FIG.5B is a graph showing the simulated response of the power divider/lowpass filter circuit 250 of FIG. 5A.

As shown in FIG. 5A, the power divider/low pass filter circuit 250 isimplemented on a microstrip printed circuit board 260. The powerdivider/low pass filter circuit 250 includes a power divider 252 and alow pass filter 254. The microstrip printed circuit board 260 mayinclude a dielectric substrate 262 that has a ground plane metallizationlayer (not shown) covering a back side of the substrate and a metal“trace” pattern 264 on the front side of the substrate 262. The tracesof the trace pattern 264 form microstrip transmission line segments andresonating stubs 266. The metal trace pattern 264 includes three “ports”which represent locations where RF signals may be input and/or outputfrom the power divider/low pass filter circuit 250. These ports includefirst and second common ports 270-1, 270-2 which form the input port anda first output port of the power divider 252, respectively, and a secondoutput port 270-3 of the power divider 252 which includes the low passfilter 254 that makes output port 270-3 a frequency selective port. Afirst trace defines a first microstrip transmission line segment 280-1that connects port 270-1 to port 270-2, and a second trace defines asecond microstrip transmission line segment 280-2 that connects port270-1 to port 270-3. The resonating stubs 266 form the low pass filter254.

FIG. 5B is a graph showing the simulated response of the powerdivider/low pass filter circuit 250 of FIG. 5A. Curve 290-1 in FIG. 5Bshows the magnitude of the signal output at port 270-2 in response to anRF signal input at port 270-1, as a function of frequency, while curve290-2 shows the magnitude of the signal output at port 270-3 in responseto an RF signal input at port 270-1, as a function of frequency. Asshown in FIG. 5B, signals in the 1427-1518 MHz frequency band that areinput to the splitter/low pass filter circuit 250 are split and outputat both ports 270-2 and 270-3, with the magnitude of the signal outputat port 270-2 being about 1 or 1.5 dB higher than the magnitude of thesignal output at port 270-3. In contrast, signals in the 1695-2690 MHzfrequency band that are input to the splitter/low pass filter circuit250 at port 270-1 pass to port 270-2 with about 3 dB attenuation at thelow portion of the frequency range and with almost no attenuation at thehigh end of the frequency range, while the signals output at port 270-3have increasing attenuation with increasing frequency.

The shape of curve 290-2 in FIG. 5B may be changed by increasing ordecreasing the number of resonating stubs 266 included in the low passfilter 254. If additional resonating stubs 266 are added, then the powerat port 270-3 decreases more quickly with increasing frequency, whereasif less resonating stubs 266 are included, then the power at port 270-3decreases more slowly with increasing frequency. Thus, the design of thefilter 254 may be used to further tune the azimuth HPBW as a function offrequency.

FIG. 6A is a graph of the simulated azimuth HPBW as a function offrequency for the second array of radiating elements 140-2 of the basestation antenna 100 of FIGS. 3A-3B when the diplexer 200 of FIG. 4A isused as the first circuit element 160 and the power divider/low passfilter circuit 250 of FIG. 5A is used as the second circuit element 170(curve 300). For purposes of comparison, FIG. 6A also includes a graphof the simulated azimuth HPBW for a comparable single column lineararray of radiating elements (curve 310).

As shown in FIG. 6A, the azimuth HPBW (curve 310) for the conventionallinear array of radiating elements varies between a low value of about55.5° and a high value of about 88°, for total variation of more than32°. This amount of variation is typically unacceptable as the largeazimuth HPBW in the lower portion of the frequency band results in lowgain values within the sector served by the linear array and highinterference levels in neighboring sectors. As shown by curve 300, thesecond array 140-2 of the base station antenna 100 according toembodiments of the present invention has an azimuth HPBW that variesbetween a low value of about 56° and a high value of about 75°, fortotal variation of only 19°, which is more than 13° less than thevariation seen for the conventional linear array.

FIG. 6B is a graph of the simulated gain as a function of frequency forthe second array 140-2 of radiating elements of the base station antenna100 of FIGS. 3A-3B implemented using the diplexer 200 of FIG. 4A as thefirst circuit element 160 and the power divider/low pass filter circuit250 of FIG. 5A as the second circuit element 170 (curve 320). Forpurposes of comparison, FIG. 6B also includes a graph of the simulatedgain for a comparable single column linear array of radiating elements(curve 330). As shown in FIG. 6B, the gain of the second array 140-2 ofbase station antenna 100 is higher than the gain of the conventionallinear array across the entire frequency range. The first and secondcircuit elements 160, 170 each introduce insertion losses which reducethe gain of the second linear array 140-2 as compared to theconventional array. However, the narrowing of the azimuth beamwidth,particularly in the lower end of the frequency range, results inincreased gain that more than offsets the insertion loss. Thus, the basestation antennas 100 according to embodiments of the present inventionmay also exhibit improved gain performance.

FIG. 7 is a graph of the simulated azimuth HPBW as a function offrequency for the second array of radiating elements 140-2 of the basestation antenna 100 of FIGS. 3A-3B implemented using the diplexer 200 ofFIG. 4A as both the first circuit element 160 and the second circuitelement 170 (curve 340). For purposes of comparison, FIG. 7 alsoincludes a graph of the simulated azimuth HPBW for a comparable singlecolumn linear array of radiating elements (curve 350).

As shown in FIG. 7, the second array 140-2 of the base station antenna100 according to embodiments of the present invention has an azimuthHPBW that varies between a low value of about 56° and a high value ofabout 75°, for total variation of only 19°, which is more than 13° lessthan the variation seen for the conventional linear array.

FIG. 8A is a schematic front view of a base station antenna 400according to further embodiments of the present invention. FIG. 8B is aschematic block diagram illustrating two of the feed networks 450 forthe base station antenna 400 of FIG. 8A.

As shown in FIGS. 8A-8B, the base station antenna 400 is similar to thebase station antenna 100 of FIGS. 3A-3B. However, the base stationantenna 400 differs from the base station antenna 100 in four ways.First, base station antenna 400 includes a third circuit element 460that may be identical to the first circuit element 160. Second, basestation antenna 400 includes a fourth circuit element 470 that may beidentical to the second circuit element 170. Third, all of the radiatingelements in base station antenna 400 are implemented as radiatingelements that operate across the full 1427-2690 MHz frequency band, andhence are labelled as radiating elements 116-1 through 116-22 in FIG.8A. Fourth, the first array 440-1 of base station antenna 400 alsoincludes radiating elements 116-10 and 116-11, which are in the secondcolumn 130-2 of radiating elements.

As can be seen from FIGS. 8A-8B, in base station antenna 400, each array440-1, 440-2 has the exact same configuration, using a pair of extracircuits to reduce the azimuth beamwidth in the lower portion of thefrequency band. The second feed network 450-2 and the second array 440-2may be identical in design and operation to the second feed network150-2 and the second array 140-2 of base station antenna 100, exceptthat output 172-2 of the second circuit element 170 is coupled to thetenth sub-array 112-10 through the third circuit element 460. Inaddition, the first feed network 450-1 and the first array 440-1 mayalso be identical in design and operation to the second feed network150-2 and the second array 140-2 of base station antenna 100, exceptthat output 472-2 of the fourth circuit element 470 is coupled to thefifth sub-array 112-5 through the first circuit element 160. As both thefirst and second arrays 440-1, 440-2 of base station antenna 400 willoperate in the same fashion as the second array 140-2 of base stationantenna 100, further description of FIGS. 8A-8B will be omitted.

FIG. 9A is a schematic front view of a base station antenna 500according to still further embodiments of the present invention thatincludes three columns 530-1 through 530-3 of radiating elements thatform three arrays 540-1 through 540-3 of radiating elements. FIG. 9B isa schematic block diagram illustrating the feed networks 550-1 through550-3 for the base station antenna 500 of FIG. 9A. Base station antenna500 is very similar to base station antenna 100 discussed above, exceptthat base station antenna 500 further includes the third column 530-3 ofradiating elements and shares radiating elements at the top of the firstcolumn 530-1 to provide a third array 540-3 that has frequency selectiveproperties.

Feed network 550-1 and array 540-1 may be identical to feed network150-1 and array 140-1 of base station antenna 100, except that (1) feednetwork 550-1 further includes an additional first circuit element 160-2that is coupled between the top sub-array of radiating elements incolumn 530-1 and the phase shifter assembly 152-1 and (2) the topsub-array of radiating elements in column 530-1 is implemented using thewider band radiating elements 116. Feed network 550-2 and array 540-2may be identical to feed network 150-2 and array 140-2 of base stationantenna 100. The third feed network 550-3 may be identical to feednetwork 550-2 except that the shared radiating elements are at the topof column 530-1.

FIG. 10 is a schematic block diagram of a base station antenna 600according to still further embodiments of the present invention that isdesigned to narrow the azimuth beamwidth differently for an array ofradiating elements in three different sub-bands. The base stationantenna 600 illustrates how the concept of using additional circuitelements such as circuit elements 160 and 170 to reduce the azimuth HPBWfor a first sub-band of an operating frequency band may be extended sothat the azimuth HPBW may be reduced for multiple sub-bands, with theazimuth HPBW for each sub-band being reduced a different amount.

As shown in FIG. 10, the base station antenna 600 is similar to the basestation antenna 100, but includes an additional first circuit element160-2 and an additional second circuit element 170-2. In thisembodiment, both first circuit elements 160-1, 160-2 are implemented asdiplexers and both second circuit elements 170-1, 170-2 are implementedas power dividers with low pass filters, although it will be appreciatedthat embodiments of the invention are not limited thereto.

As shown in FIG. 10, the base station antenna 600 is identical to basestation antenna 100 except that (1) the first diplexer 160-1 is onlycoupled to the bottom radiating element 116 in the first column 130-1,(2) the first divider/filter 170-1 is only coupled to the bottomradiating element 116 in the second column 130-2, (3) a second diplexer160-2 is provided that is coupled to the next to bottommost radiatingelement 116 in the first column 130-1, and (4) a second divider/filter170-2 is provided that is coupled to the next to bottommost radiatingelement 116 in the second column 130-2. The second diplexer 160-2 andthe second divider/filter 170-2 are configured to allow the next to thebottommost radiating element in the first column 130-1 to be sharedbetween the two arrays 640-1, 640-2, but for different frequency rangesas compared to the bottommost radiating element in the first column130-1.

In an example embodiment, the first diplexer 160-1 may be implemented tohave a 1427-1518 MHz frequency selective port 162-2, a 1695-2690 MHzfrequency selective port 162-1 and a common port 162-3. The seconddiplexer 160-2 may be implemented to have a 1695-2690 MHz frequencyselective port 164-1, a 1427-2200 MHz frequency selective port 164-2 anda common port 164-3. The first diplexer/filter 170-1 may be implementedas a power divider having a port with a low pass filter with a nominalcutoff frequency between 1518 MHz and 1695 MHz as well as first andsecond common ports 172-2, 172-3. The second diplexer/filter 170-2 maybe implemented as a power divider having a port 174-1 with a low passfilter with a nominal cutoff frequency between 2200 MHz and 2300 MHz aswell as first and second common ports 174-2, 174-3.

The first array 640-1 of radiating elements of base station antenna 600will, like the first array 140-1 of base station antenna 100, operate asa linear array of radiating elements for RF signals that are anywherewithin the 1427-2690 MHz frequency range. The second array 640-2 ofradiating elements of base station antenna 600 will, like the firstarray 140-2 of base station antenna 100, operate as a linear array ofeleven radiating elements 116-1 through 116-11 for RF signals that arewithin the 2300-2690 MHz frequency range. The second array 640-2 ofradiating elements will, like the second array 140-2 of radiatingelements of base station antenna 100, operate as a two column array thatincludes all eleven elements in column 130-2 as well as the bottom tworadiating elements of column 130-1 for RF signals that are within the1427-1518 MHz frequency range. The second array 640-2 of radiatingelements differs from the second array 140-2 of radiating elements ofbase station antenna 100, however, in that it will operate as a twocolumn array that includes all eleven elements in column 130-2 as wellas the next to bottommost radiating element of column 130-1 for RFsignals that are within the 1695-2200 MHz frequency range, whereas thesecond array 140-1 of radiating elements of base station antenna 100operates as a linear array for such signals. The base station antenna600 may further reduce the variation in the azimuth HPBW across the1427-2690 MHz frequency band.

The base station antenna 600, therefore, includes first and second RFports 120-1, 120-2 and first and second horizontally offset verticalcolumns 130-1, 130-2 of radiating elements. More than half of theradiating elements in the first vertical column 130-1 are part of afirst array 640-1 of radiating elements that is coupled to the first RFport 120-1 through a first feed network 150-1, and more than half of theradiating elements in the second vertical column 130-2 are part of asecond array 640-2 of radiating elements that is coupled to the secondRF port 120-2 through a second feed network 150-2. The second array640-2 of radiating elements includes a first number of the radiatingelements (here zero) in the first column 130-1 for RF signals that arewithin a first frequency range (here the 2300-2690 MHz frequency range)and a second number of the radiating elements (here one) in the firstcolumn 130-1 for RF signals that are within a second frequency range(here the 1695-2200 MHz frequency range) that is lower than the firstfrequency range, the second number being larger than the first number.The second array 640-2 of radiating elements includes a third number(here two) of the radiating elements in the first column 130-1 for RFsignals that are within a third frequency range (here the 1427-1518 MHzfrequency range) that is lower than the second frequency range, thethird number being larger than the second number.

Embodiments of the present invention have been described above withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being “on”another element, it can be directly on the other element or interveningelements may also be present. In contrast, when an element is referredto as being “directly on” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present. Other words used to describethe relationship between elements should be interpreted in a likefashion (i.e., “between” versus “directly between”, “adjacent” versus“directly adjacent”, etc.).

It will be understood that the terms “comprises” “comprising,”“includes” and/or “including” when used herein, specify the presence ofstated features, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,operations, elements, components, and/or groups thereof.

Aspects and elements of all of the embodiments disclosed above can becombined in any way and/or combination with aspects or elements of otherembodiments to provide a plurality of additional embodiments.

In the drawings and specification, there have been disclosed typicalpreferred embodiments of the invention and, although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the invention being set forthin the following claims.

That which is claimed is:
 1. A base station antenna, comprising: a firstradio frequency (“RF”) port; a second RF port; a first array ofradiating elements that is coupled to the first RF port; a second arrayof radiating elements that is configured to operate in a frequency rangethat includes a first sub-band and a second sub-band, the second arrayof radiating elements coupled to the second RF port; wherein a first ofthe radiating elements in the first array of radiating elementscomprises a first shared radiating element that operates as part of thesecond array of radiating elements when the second array of radiatingelements operates in the first sub-band and which does not operate aspart of the second array of radiating elements when the second array ofradiating elements operates in the second sub-band.
 2. The base stationantenna of claim 1, wherein the first sub-band comprises lowerfrequencies than the second sub-band.
 3. The base station antenna ofclaim 2, wherein the first sub-band is at least a portion of the1427-1518 MHz frequency band and the second sub-band is at least aportion of the 1695-2690 MHz frequency band.
 4. The base station antennaof claim 1, wherein a second of the radiating elements in the firstarray of radiating elements comprises a second shared radiating elementthat operates as part of the second array of radiating elements when thesecond array of radiating elements operates in the first sub-band andwhich does not operate as part of the second array of radiating elementswhen the second array of radiating elements operates in the secondsub-band.
 5. The base station antenna of claim 1, wherein all ofradiating elements in the first array of radiating elements areidentical.
 6. The base station antenna of claim 1, wherein the firstshared radiating element has a different design than at least some ofthe radiating elements in the first array of radiating elements.
 7. Thebase station antenna of claim 1, wherein the first array of radiatingelements consists of a first column of radiating elements and the secondarray of radiating elements consists of a second column of radiatingelements when operating in the second sub-band and comprises the secondcolumn of radiating elements and the first shared radiating element whenoperating in the first sub-band.
 8. The base station antenna of claim 1,wherein the frequency range is a second frequency range, wherein thefirst array of radiating elements is configured to operate in a firstfrequency range, and wherein the second frequency range partially, butnot completely, overlaps with the first frequency range.
 9. The basestation antenna of claim 1, wherein the frequency range is a secondfrequency range, wherein the first array of radiating elements isconfigured to operate in a first frequency range, and wherein the firstfrequency range is identical to the second frequency range.
 10. The basestation antenna of claim 1, wherein the frequency range is a secondfrequency range, wherein the first array of radiating elements isconfigured to operate in a first frequency range, and wherein the firstfrequency range is identical to the second frequency range.
 11. A basestation antenna, comprising: a first radio frequency (“RF”) port; afirst column of radiating elements that comprises at least a portion ofa first array of radiating elements, the first array of radiatingelements coupled to the first RF port; a second RF port; a phase shifterassembly that is connected to the second RF port; a second column ofradiating elements that comprises at least a portion of a second arrayof radiating elements that is configured to operate in a frequency rangethat includes a first sub-band and a second sub-band, the second arrayof radiating elements coupled to the second RF port via the phaseshifter assembly; wherein a first output of the phase shifter assemblyis only coupled to one or more of the radiating elements in the secondcolumn of radiating elements for RF signals in the second sub-band, andwherein the first output of the phase shifter assembly is coupled to oneor more of the radiating elements in the first column of radiatingelements for RF signals in the first sub-band.
 12. The base stationantenna of claim 11, wherein the first output of the phase shifterassembly is also coupled to one or more of the radiating elements in thesecond column of radiating elements for RF signals in the firstsub-band.
 13. The base station antenna of claim 12, wherein the firstoutput of the phase shifter assembly is connected to the one or more ofthe radiating elements in the second column of radiating elements and tothe one or more of the radiating elements in the first column ofradiating elements via a diplexer.
 14. The base station antenna of claim11, wherein the first output of the phase shifter assembly is notcoupled to any of the radiating elements in the second column ofradiating elements for RF signals in the first sub-band.
 15. The basestation antenna of claim 14, wherein the first output of the phaseshifter assembly is connected to the one or more of the radiatingelements in the first column of radiating elements via a power divider,and is connected to the one or more of the radiating elements in thesecond column of radiating elements via the power divider and a low passfilter.
 16. The base station antenna of claim 11, wherein the firstsub-band is at lower frequencies than the second sub-band.
 17. The basestation antenna of claim 11, wherein the frequency range is a secondfrequency range, wherein the first array of radiating elements isconfigured to operate in a first frequency range, and wherein the secondfrequency range partially, but not completely, overlaps with the firstfrequency range.
 18. A base station antenna, comprising: a radiofrequency (“RF”) port; a first set of radiating elements that is coupledto the RF port; a second set of at least one radiating element that iscoupled to the RF port; a third set of at least one radiating elementthat is selectively coupled to the RF port; wherein the first set ofradiating elements and the second set of at least one radiating elementare coupled to the RF port and the third set of at least one radiatingelement is not coupled to the RF port for RF signals in a secondfrequency sub-band, and at least the first set of radiating elements andthe third set of at least one radiating element are coupled to the RFport for RF signals in a first frequency sub-band.
 19. The base stationantenna of claim 18, wherein the first set of radiating elements and thesecond set of at least one radiating element comprise a first column ofradiating elements, and the third set of at least one radiating elementcomprises part of a second column of radiating elements that ishorizontally offset from the first column of radiating elements.
 20. Thebase station antenna of claim 18, wherein the second frequency sub-bandis at higher frequencies than the first frequency sub-band.
 21. The basestation antenna of claim 18, wherein the second set of at least oneradiating element is also coupled to the RF port for RF signals in thefirst frequency sub-band.
 22. The base station antenna of claim 18,wherein the second set of at least one radiating element is not coupledto the RF port for RF signals in the first frequency sub-band.